Capping device



May 27, 1969 .J o. HoRsLEY 3,446,253

` CAPPING DEVICE Filed Feb. 24, 1967 'sZM/Z/Zmz.

` A-rronusrs United States Patent O 3,446,268 CAPPING DEVICE Jack 0. Horsley, Trenton, Mich., assigner, by mesne assignments, to Concast Incorporated, New York, N.Y., a corporation of Delaware Filed Feb. 24, 1967, Ser. No. 618,487 Int. Cl. B22d 11/08 U.S. Cl. 164-274 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to continuous casting and, more particularly, relates to an improved device for capping the end of a continuously cast slab.

In the production of steel ingots, and particularly rimming steel ingots, it has been a common practice to cap the ingot after pouring has been completed in order to stop gassing and bleeding of the ingot. Before the steel is permitted to cool, it is essential to insure that the trailing end of the slab is solidified and that gassing and bleeding is stopped promptly. Customarily, the rimming action, which is caused by the reaction of oxygen and carbon in the molten steel, is terminated by deoxidizing the steel with, for example, aluminum or some other deoxidizing agent. However, when aluminum bars or shot are dropped into the molten portion of a continuously cast slab, the tinal 3 to 6 feet of the slab becomes contaminated and must be scrapped. Such a scrap loss reduces the yield of the cast substantially. For example, a 3 foot length of slab, 6 inches thick, is suicient to produce about 160 feet of hot rolled strip 0.090 inch thick. This excessive scrap loss is due to the fact that the molten stream of steel from the tundish drives the aluminum shot deep into the molten portion of the cast slab. Additionally, it was believed that the aluminum shot thrown into the mold caused scratching and grooving of the mold.

Thus, the primary object of the lpresent invention is to provide an improved capping device which effectively caps the trailing end of a continuously cast slab and reduces the contamination of the end of the slab thereby increasing the yield of the cast.

In accordance with this object, there is provided, in a preferred embodiment of the present invention, a capping device consisting of a base plate having an outline coniiguration matching the mold cavity but of reduced dimension so as to iit easily therein. A sheet metal can is formed about the base plate. Short lengths of bars of deoxidizer such as aluminum are coupled to the bottom of the base plate. At the end of casting a strand, the capping device is lowered into the mold and into engagement with the metal therein. The deoxidizer bars sink into the molten metal to kill the steel, stopping the reaction of oxygen and carbon. The gas expelled from the slab together with any metal which might bleed from the slab passes between the ends of the base plate and the encircling formed can. Thereafter, water is sprayed into the can to complete the capping off process. In this manner, contamination of the strand is limited to the short insertion distance of the deoxidizer bars.

Having briefly-'described this invention, it will be described in greater detail along with other objects and advantages in the following portions of the specication, which may best be understood by reference to the accompanying drawings, of which:

FIG. 1 is a partially sectioned elevation View of a capping device in accordance with the present invention;

FIG. 2 is a partially sectioned plan view of a capping device in accordance with the present invention.

In the figures, there is shown the improved capping device which comprises a steel base plate 10 which may, for example, be of the order of 1/2 inch thick having a pair of lifting rings 12 welded to the upper surface of the plate.

A -sheet metal can 14 made from thin sheet metal, for example, 16 or 18 gauge sheet steel, is formed into a hollow rectangular box about 6 inches deep and attached to the long edges of the base plate 10. The end of the can 14 extends approximately 2 inches beyond each end of the base plate 10. Protection shields 16 and 18, preferably made from asbestos sheets about 3A; inch in thickness, and slightly shorter than the length of the can 14 are attached to the can with wires 20 which preferably are made of aluminum. Aluminum bars 22 weighing approximately 3 pounds each broken from a standard aluminum ingot are attached to the lower surface of the base plate 10. 4No special shape is required for the aluminum bars 22 and, therefore, a bar of any convenient shape may be utilized.

The overall dimensions of the improved capping device may be varied according to the size of the mold with which the capping device is to be used. For example, if the capping device is to be used in a 10 inch by 52%; inch mold, the outside dimensions of the capping device, exclusive of the asbestos shields, may be 9 inches by 501/2 inches, thus providing approximately 1/2 inch clearance on each of the long sides of the mold and about 1 inch on each end of the mold. Similar clearances would be applicable to molds varying in size from 6 inches by 24 inches to 14 inches by 80 inches.

At the end of the cast, the capping device of the present invention, suspended by the lifting rings 12, is lowered into the mold, the asbestos shields 16 and l18 serving to prevent the mold Walls from being scratched. As the aluminum bars 22 sink into the molten surface of the steel within the mold, the molten metal is killed and quickly frozen. The gas expelled from the slab together with any metal which may bleed from the slab passes through the spaces between the ends of the plate 10 and the sheet metal can. In the event of excess bleeding or if the rimming action is not completely terminated, one or more small bags of aluminum shot may be placed at the Iareas where bleeding is occurring. Thereafter, water is sprayed into the can 14 to complete the capping off process.

Since the aluminum bars 22 are maintained near the end of the cast slab and away from the Walls of the mold, the contamination of the slab by the aluminum is limited to `a short portion of the end of the slab. As a result, the portion of the slab which must be scrapped due to contamination has been reduced from about 3 to 6 feet to about 9 inches, thereby increasing the yield of the cast slab substantially. The steel base plate 10 also serves to reinforce the end of the cast slab during the remainder of the solidiiication process and inhibits the possibility of slab bleeding during this period.

Of course, a number of variations may be made in the improved capping device described above. For example, the aluminum bars may be replaced with other deoxidizing materials such -as magnesium, calcium, silicon, etc. Also, the dimensions of the various parts may be varied to meet the requirements of a particular operation and the amount of aluminum or other deoxidizers used may vary with the degree of deoxidation needed. Finally, asbestos shields 16 and 18 could be provided Afor the ends of the improved capping device though no need for such additional shields has become apparent.

This invention may be variously modified and embodied within the scope of the subjoined claims.

What is claimed is:

1. A capping device for the terminal end of a continuously cast strand which comprises a base plate, a thin Walled can mounted on said base plate and having portions thereof separated from said base plate to provide spaces therebetween, deoxidizer bars suspended from the bottom of said base plate, said capping device being inserted into the continuous casting mold and positioned on the molten metal therein so that said deoxidizer bars sink into s'aid molten metal to kill said metal, said spaces providing a venting means for venting of gas from said strand to the atmosphere.

2. A capping device in accordance with claim 1 in which said deoxidizer bars are selected from the group consisting of aluminum, magnesium, calcium and silicon.

3. A capping device in accordance with claim 1 ywhich includes asbestos shields positioned along at least two of the Walls of said can to protect the mold Walls from contact with said can.

, 4. A capping device in accordance with claim 1 in which said base plate is provided with lifting rings at the top surface thereof.

References Cited UNITED STATES PATENTS 2,591,517 4/1952 Daussarr 164-57 X 2,876,509 3/1959 Gardner 164-281 2,879,156 3/1959 Hurum.

2,891,291 6/1959 Schnack@ 164-281 x 2,978,765 4/1961 Brown 164-56 FOREIGN PATENTS 695,394 10/1964 Canada. 906,478 9/1962 GrearBrit-airr.

I. SPENCER OVERHOLSER, Primary Examiner.

R. SPENCER ANNEAR, Assistant Examiner. 

